1. Field of the Invention
The present invention relates to the structure of a track guiding guard which is designed to protect track rollers of a crawler or track type vehicle.
2. Description of the Prior Art
A typical conventional track guiding guard for protecting track rollers of a crawler type vehicle includes, as shown in FIGS. 3 and 4, a pair of long left and right guard members 5 which rotatably support track rollers 3 under a track frame 1, the track rollers 3 being properly spaced apart from each other in the longitudinal direction. The track rollers 3 guide track links 9 which are secured to the upper surface of each track shoe 7 and engaged with the track rollers 3. Each guard member 5 includes a side plate 11 of continuous length which rotatably supports one end of each track roller 3, U-shaped brackets 13 which are secured to the side plate 11, and an upper plate 15 and a guide 17 which are of continuous length and are secured to the upper and lower ends, respectively, of the side plate 11 and all of them are secured together in one unit. The upper plate 15 is secured to the lower end of the track frame 1 by means, for example, of bolts 19.
The track guiding guard 10 having the arrangement described above is, when the vehicle travels on a flat land, in the state shown in FIG. 4. However, when the vehicle moves over irregular land or works on a slope, the track frames 1 are inclined relative to the track shoes 7 which are left in close contact with the ground, as shown in FIG. 5. As a result, the track rollers 3 are subjected to a force which acts in such a manner as to lift them upwardly at one end thereof and thereby tend to disengage them from the track links 9. At this point, the guide 17 at the lower end of the one guard member 5 abuts against the outer ends of track pins 21, thereby limiting the inclination, and thus preventing the track rollers 3 from disengaging from the track links 9.
In the above-described prior art, however, if the limit angle .theta. of inclination of the vehicle body relative to the track shoes 7 or the track links 9 is set at an excessively small angle, when the vehicle moves over irregular land, bumps are likely to be transmitted from the track shoes 7 to the vehicle body, thus causing discomfort to the driver. On the other hand, if the limit angle .theta. of inclination is set at an excessively large angle, the moment about the mounting bolts 19 that is caused by a force acting on the guide 17 from track pins at the lower end of the guard member 5 is too large and it is therefore likely that the guard member 5 or the mounting bolts 19 will be broken. If the angle .theta. of inclination exceeds the critical angle of slip between the track rollers 3 and the track links 9, the track links 9 disengage from the track rollers 3, as shown in FIG. 6, which accelerate the nonuniform or local wear of the track rollers 3 and the track links 9. Further, since the horizontal distance l between supporting points P1 and P2 where moment is born when the vehicle body is inclined is short, the prior art has inferior stability.